Windows are commonly used on vehicles to provide protection from the elements while preserving visual acuity. Several examples of vehicles that benefit from the use of windows include spacecraft, aircraft, automobiles, boats, motorcycles, and trucks.
Conventional windows have only a single transmissivity state. Specifically, conventional windows transmit virtually all incoming light regardless of the ambient conditions (e.g., rain or shine, dusk or dawn, or noon or night). Such single state windows may be optimized for use under certain circumstances, such as periods of low incoming light (e.g., when a vehicle is traveling away from the sun or at night). However, under other circumstances such as periods of high incoming light (e.g., when a vehicle is traveling toward the sun or instruments are reflecting backlighting from the sun), or transitional periods of lighting where a lighting level is changing rapidly (e.g., when flying at an altitude with intermittent cloud cover), a window with other transmissivity states may be desired to minimize operator discomfort and improve visual acuity.
In an effort to minimize operator discomfort and improve visual acuity, vehicles with conventional windows are typically provided with sun shades or sun visors. However, sun shades and sun visors offer only limited protection. For example, sun shades may reduce transmissivity, but they are not capable of adapting to changing light conditions. Sun visors also reduce transmissivity—perhaps to zero—but generally cover only a portion of the surface area of the window. As such, operators of vehicles with conventional windows commonly rely upon sun glasses in addition to sun shades and sun visors to manually manage incoming light.
In recent years, variably dimmable windows have been developed as an alternative to conventional windows. The transmissivity of a variably dimmable window can be controlled electronically, such as by controlling a voltage or electric field applied to the window. As such, variably dimmable windows present the opportunity to reduce or eliminate the need for mechanical devices, such as sun shades and sun visors, on vehicles. Variable dimmable windows also offer a potential for automation in order to reduce operator workload.
Accordingly, those skilled in the art continue with research and development efforts in the field of variably dimmable windows.